Roton dipole moment

The roton excitation in the superfluid He-4 does not possess a stationary dipole moment. However, a roton has an instantaneous dipole moment, such that at any given moment one can find it in the state either with positive or with negative dipole moment projection on its momentum direction. The instantaneous value of electric dipole moment of roton excitation is evaluated. The result is in reasonable agreement with recent experimental observation of the splitting of microwave resonance absorption line at roton frequency under external electric field.Comment: 5 page

Theory of a Narrow roton Absorption Line in the Spectrum of a Disk-Shaped SHF Resonator

We calculate the probability of the birth of a circular phonon (c-phonon) in He II by a c-photon of the resonator. It is shown that this probability has sharp maxima at frequencies, where the effective group velocity of the c-phonon is equal to zero; the density of states of c-phonons strongly grows at such frequencies. For He II, these frequencies correspond to a roton and a maxon. From the probability of the c-roton birth, we calculate the roto line width which is found to approximately agree with the experimental one. We conclude that the roton line observed in the super-high-frequency (SHF) absorption spectrum of helium is related to the birth of c-rotons. A possible interpretation of the Stark effect observed for the roton line is also proposed.Comment: 13 pages, 1 figure, v2: journal variant, several minor correction

On the electric activity of superfluid systems

The Keldysh's theory of superfluidity of rarefied electron-hole gas is generalized to a case of possible pair polarizability. It was shown that inhomogeneity of the system leads to dipole moment which is proportional to the density gradient. The dipole moment appears also near boundaries of the system. It was determined that quantized vortices in a magnetic field carry a real electric charge. In He II at H=10 T and helium rotation velocity $10^2$ s$^{-1}$ the charge density is about $10^4e$ cm$^{-3}$, where $e$ is the electron charge.Comment: 5 pages V. 2: replaced incorrect g valu

A search for disordered (glassy) phase in solid 3He deformed in situ

A disordered (glassy) state has been searched in solid 3He deformed in the course of experiment employing precise measurements of pressure. The analysis of the temperature dependence of the crystal pressure measured at a constant volume shows that the main contribution to the pressure is made by the phonon subsystem, the influence of the disordered phase being very weak. Annealing of the deformed crystal does not affect this state. The results obtained differ greatly from the corresponding data for solid 4He measured in the region of supersolid effects where a pressure excessive in comparison to the phonon one was registered. The excess pressure had a quadratic dependence on temperature, which is typical of a disordered system. Absence of the excess pressure in solid 3He is unclear yet, some speculative interpretations are suggested.Comment: 9 pages, 4 figure

Новый метод исследования динамических моделей приводов машин с распределенными параметрами

Запроваджено новий метод дослідження динамічних моделей приводів гірничих, будівельних та сільськогосподарських машин.The new method of research of dynamical models of mining building agricultural machines drives is proposed.Предложен новый метод исследования динамических моделей приводов горных, строительных и сельскохозяйственных машин

Применение обобщенного метода Бубнова-Галеркина к решению динамических нестационарных задач виброударного уплотнения вязкоупругих материалов

Розв’язана динамічна нестаціонарна задача віброударного ущільнення в’язкопружних матеріалів (тіла Максвелла) за допомогою узагальненого методу Бубнова-Гальоркіна.The dynamic unstationary task of vibroimpact compression of viscoelastic materials (bodies of Maxwell) through the generalized method Bubnova-Gal’orkina is decided.Решена динамическая нестационарная задача виброударного уплотнения вязкоупругих материалов (тела Максвелла) при помощи обобщенного метода Бубнова-Гальоркина

Measurements of the Complex Permittivity of Liquid Helium-4 in the Millimeter Wave Range by a Whispering Gallery Mode Resonator

We report experimental study of electrical properties of liquid helium-4 in the temperature range 1.2-3 K. The experiment is carried out in the millimeterwave range using a whispering-gallery-mode dielectric resonator, and the complex permittivity of liquid helium is extracted from the data using the resonant perturbation method. The results for temperature dependence of the dielectric constant are consistent with the previous studies. In addition, we find strong enhancement of the loss tangent around the superfluid transition temperature

On the mutual polarization of two He-4 atoms

We propose a simple method based on the standard quantum-mechanical perturbation theory to calculate the mutual polarization of two atoms He^4.Comment: 9 pages, 1 table; the article is revised and the calculation is essentially refined; v4: final version, the Introduction is delete